A. Field of the Invention The present invention relates to a method and device for directing circuit-switched connections carrying on-line data to an on-line service such as the Internet. More particularly, the present invention relates to a device and method for switching telephone calls to the dial-up access lines of Internet Service Providers.
B. Description of the Related Art
In the past, most telephone service subscribers have used telephone service for placing ordinary voice calls. Plain old telephone service ("POTS") is typically delivered over a subscriber loop between the subscriber's home or office and the local telephone company central office. The telephone company central offices provide a circuit-switched network to establish connections between subscribers wishing to communicate. In such a circuit-switched system, a circuit connection is established and maintained for the duration of each telephone call.
Recently, the popularity of on-line computer data services such as the Internet has changed the way subscribers use their telephone service. Rather than placing voice telephone calls, subscribers now use their telephones to access on-line computer data services such as the Internet. In contrast to voice telephone calls, which are relatively short in duration, the average telephone call carrying computer data to the Internet is many times longer. These longer hold time telephone calls tie up the telephone company's switching equipment which was designed for shorter duration telephone voice calls. The public switched telephone network ("PSTN") and associated circuit-switching equipment was designed to be shared by only a fraction of subscribers actually using the telephone at any time. PSTN includes those public switched telephone networks provided by AT&T, Regional Bell Operating Companies (e.g., Ameritech, U.S. West, Bell Atlantic, Southern Bell Communications, Bell South, NYNEX, and Pacific Telesis Group) and others. The PSTN was designed with the assumption that only about 12% of residential users and 20% of business users will be on the telephone at any given time. Now, many more households are using the telephone for longer durations than the system had ever been designed to handle.
In addition to longer duration telephone calls, the increasing number of telephone calls to access on-line data services has increased the volume of call traffic in the PSTN. In particular, the trunk facilities into the central offices which contain telephone numbers providing telephone dial-up access to Internet Service Providers ("ISP") have seen a dramatic increase in call traffic, which is expected to continue to grow. These terminating offices providing access to ISPs have seen the most growth in call traffic and thus the greatest potential for call congestion. Because of the load on the network, customers may experience longer waits for dial tone, longer connection times, and even the blocking of telephone calls. If not addressed, call congestion in these offices may result in a degradation of the quality of telephone service to all customers. ISPs are expected to request high-capacity trunk connections to the PSTN at these offices at an increasing rate.
To address the increasing call duration and traffic, network equipment suppliers have proposed segregating telephone calls to ISPs to be carried on separate data networks. For example, telephone calls to telephone numbers providing access to ISPs may be routed to a packet-switched data network that efficiently carries high-speed digital data traffic. A packet-switched network establishes a virtual circuit connection that, rather than maintaining a connection for the duration of the telephone call, uses transmission resources only when data is actually transmitted. Such a virtual connection is well suited for users of computer services who are connected for long periods of time but only spend a relatively small proportion of time actually transmitting and receiving data. Packet networks, however, have not yet been as widely deployed and would require substantial new investments in network equipment. Packet data solutions also require new network elements, new operational processes, resources, and the ISP adoption of network based modem solutions to allow subscribers access to the packet data network.
In the interim, telephone companies have adjusted the configuration of their existing PSTN circuit-switched network. For example, telephone companies have rebalanced their central offices to evenly distribute the load of high usage subscribers throughout the equipment. Additionally, trunking and switching equipment throughout the entire network has been expanded to handle the increased call traffic. Increasing the capacity of the entire network, however, is costly and does not necessarily generate additional revenue to cover the cost of the additional equipment. Moreover, introducing increasing switching and trunking capacity throughout the entire network is disruptive, and difficult to administer and manage.
In accordance with an illustrative embodiment of the present invention, the problems of handling an increased volume of telephone calls to on-line data services can be reduced.